This invention relates to improvements in a flat package semiconductor device used as a high power semiconductor rectifier element, a high power transistor or the like, and more particularly to improvement in ability of such a device to withstand a rupture due to a flow of shortcircuit current through the device.
Lately it is being strongly promoted to make semiconductor devices and particularly power semiconductor devices high-powered and/or small sized. However, as the current capacity of semiconductor devices becomes higher, it has been difficult to protect the semiconductor devices by associated fuses and to bring the devices and fuses into harmony. Where a suitable fuses can not be available, a shortcircuit current flowing through a mating semiconductor device is, in the worst case, equal to several times its rating surge current within a few cycles of the system current until the fuse is blown. If this shortcircuit current is sufficiently high then it melts only a semiconductive material, for example, silicon forming of a semiconductor element disposed in the semiconductor device but also electrodes formed on the semiconductor element of a good thermally and electrically conductive material such as copper or aluminum. In addition, an inert gas filling the semiconductor device may be expanded resulting in an explosion occurring therein. This explosion of the gas might bring about a serious damages to and an important disasters of external devices.
Accordingly, it is an object of the present invention to provide a new and improved flat package semiconductor device free from a danger that any explosion will occur even though an excessive shortcircuit current would flow therethrough.
It is another object of the present invention to provide a new and improved flat package semiconductor device having a resistance to mechanical vibrations sufficient to prevent the airtightness from being injured with any vibration having a high acceleration and applied to the device for a long time.